20091230, 20:31  #1 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
2^{5}·3^{3}·5 Posts 
Peculiar activity in the 1M range...
I just noticed that the nonprime exponents between 1,000,000 and 1,005,000 have all been quadruple LL tested recently and many of them have had a couple dozen P1 tests run with progressively larger B1/B2 combos all by the same user. i.e.
Code:
1001911 No factors below 2^61 P1 B1=4200000, B2=4300000 Verified LL 373C by "David Slowinski" Verified LL 7EB3104CB7A0373C by "Terry S. Arnold" Verified LL 7EB3104CB7A0373C by "Brian J. Beesley" Verified LL 7EB3104CB7A0373C by "Rob_Dee" on 20091223  snip  History no factor from 2^60 to 2^61 by "Sturle Sunde" on 20090215  snip  History B1=1100000, B2=11000000 by "Rob_Dee" on 20091215 History B1=1200000, B2=12000000 by "Rob_Dee" on 20091215 History B1=1400000, B2=1500000 by "Rob_Dee" on 20091216 History B1=1600000, B2=1700000 by "Rob_Dee" on 20091217 History B1=1800000, B2=1900000 by "Rob_Dee" on 20091218 History B1=2000000, B2=2100000 by "Rob_Dee" on 20091219 History B1=2200000, B2=2300000 by "Rob_Dee" on 20091220 History B1=2400000, B2=2500000 by "Rob_Dee" on 20091221 History B1=2600000, B2=2700000 by "Rob_Dee" on 20091222 History B1=2800000, B2=2900000 by "Rob_Dee" on 20091223 History 7EB3104CB7A037__ by "Rob_Dee" on 20091223 History B1=3000000, B2=3100000 by "Rob_Dee" on 20091224 History B1=3200000, B2=3300000 by "Rob_Dee" on 20091225 History B1=3400000, B2=3500000 by "Rob_Dee" on 20091226 History B1=3600000, B2=3700000 by "Rob_Dee" on 20091227 History B1=3800000, B2=3900000 by "Rob_Dee" on 20091228 History B1=4000000, B2=4100000 by "Rob_Dee" on 20091229 History B1=4200000, B2=4300000 by "Rob_Dee" on 20091230 If he is choosing to do these assignments  it's a free country. If, on the other hand, he doesn't understand the testing process he may not be aware that he is essentially doing a lot of unnecessary work. Last fiddled with by petrw1 on 20091230 at 20:32 Reason: spelin' 
20091231, 01:01  #2 
"Mark"
Feb 2003
Sydney
3×191 Posts 
I wonder how many factors they've found? Unfortunately, although PrimeNet tells us who did the unsuccessful factoring efforts, it does not tell us who was successful and found a factor.

20091231, 04:30  #3 
"Lucan"
Dec 2006
England
2×3×13×83 Posts 
Love the risquee title of this thread
Last fiddled with by davieddy on 20091231 at 04:31 
20110114, 13:56  #4  
Mar 2010
Morgantown, WV
35_{8} Posts 
Quote:
As I know very little about the math involved in Prime95, and understand even less, it seems to me that P1 testing is successful very rarely due to the unique properties a factor would have to have in order to be found by it: to have all factors of the factor  1 be less than B1, or only one between B1 and B2. I don't know what the success rate has been for GIMPS's P1 efforts finding factors, but I expect it to be less than 5%, and not just because bounds are picked which provide the best timesaving and often result in having probabilities of success of 6% and lower. I factored the factors of the 116 largest factors reported to PrimeNet in order to see what bounds would have discovered them, only 3 had largest P1 factor less than 9 digits in size. I do realize, however, that P1 will find any factor of an exponent as long as the factor's factors meet the P1 criteria, and smaller factors probably are morelikely to do so. I really did the test I did to see if P1 was at all a good idea to try to find the large factor waiting to be found for M1061. Still, it seems to me that using P1 to find factors for M999959 and M1000003 is a bad idea, but by incrementing the search as he is Rob is at least building a cummulative effort and perhaps making the best of a bad situation. What say you experts, is Rob onto something or using good cycles in a notsogood way? While I have your "ears" on P1, would you rather a P1 tester use a large B1 and let B2=B1, or should one use the recommended B1 and B2 for an exponent? Best of luck to Rob! 

20110114, 16:51  #5  
Apr 2007
Spessart/Germany
2·3^{4} Posts 
Quote:
But was it a bad idea? This depends on what he wanted. To find a factor of the Mersennenumber it was a bad idea. To get many 'GHzdays' on the P1 topproducer list it was a 'good' idea. It is possible to copy the savefile of prime95 while doing a stage 2 of a P1 factoring. After finishing the P1 and posting the result, you can recopy the savefile and start a P1 with larger B1 (but only a little bit larger as before). Now you only need to do a stage 1 from the old B1 up to the new B1 which will save some time. But after finishing the new P1 you will get the same amount of 'GHzdays' from the server as if you did the new P1 completely. There were already some discussions in some threads about this problems, and I think in the meantime George Woltman is looking for such 'small expandations' of P1 and subtracts the 'bad GHzdays' Quote:
A P1 factoring with B1,B2 'knows' about the congruence A ECM curve with the same boundaries B1,B2 doesn't 'know' anything about this congruence. Thus a P1 with B1,B2 is the fastetst ECMcurve with this boundaries and it is the curve with the highest probability to find a factor. But it is only *one* curve, it is not needed to do a P1 with nearly the same boundaries on a Mersennenumber (or another number) again. If I want to make a new P1 on a Mersennenumber I'm choosing at least new B1 >= 4* old B1 (most times B1(new)=10*B1(old)) and B2 as large as possible... Quote:
Quote:
greetings Matthias 

20110114, 18:01  #6 
Mar 2010
Morgantown, WV
29 Posts 
Matthias, I do not know how to adequately thank you for the insight and information you have provided me, both on this thread and my M4219 thread. I am always worried about being skewered by Dr. Silverman as well as the other very knowledgable people on this forum because I don't know enough to even form the most basic questions in most cases, but you come along and offer in depth yet easy to follow explanations and do so with a friendly, helpful, and encouraging manner. Truly, thank you.
I have had a busy morning and my brain is even less able to try to understand what you have said, but I will continue trying and hope I will not lose your patience should I have additional questions. Thank you again. 
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